1. Field of the Invention
The present invention relates to the lifting of objects and particularly to the raising of vehicles to an elevated position in the interest of facilitating the servicing thereof. More specifically, this invention is directed to lift mechansims of the elevator bridge type wherein a load is supported on a vertically movable member or members which extend transversely between vertical columns. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
Elevator bridges or lifts employing a pair of vertical columns which guide a vertically movable horizontal load supporting member are known in the art. Lifts of this type have the disadvantage that they can only be employed with comparatively lightweight loads. Also, the vertically movable support member which extends between the columns must be of a rather substantial size when compared to the load and thus, in the case of a lift designed for the raising of motor vehicles, the support member impedes access to certain parts of the vehicle.
Elevator bridge type lifts with four columns are also known. Such four column units employ a pair of horizontally oriented support members guided in pairs of columns. The support members in turn support transversely oriented parallel runways. In such four column lifts the runways impede access to certain parts of the vehicle being serviced and, because the vehicle rests oon its wheels, a number of adjustments and checking operations are not possible. In order to obviate these drawbacks it has been proposed to place jacks on the runways in order to raise the vehicle in relation to the runways. For obvious reasons, including the inability to obtain sufficient clearance between the runway and vehicle, the use of such auxiliary jacks is an unacceptable solution. In addition, the use of a plurality of jacks mounted on the runways is an expensive and complicated approach which carries with it an inherent safety risk.